Whisk the dry ingredients: In a large bowl, sift together the flour, sugar, baking powder, bicarbonate of soda and salt. The mixture should be pale and uniform, with no lumps of leavener. Set aside.

Prepare the wet base: In a separate jug, whisk the buttermilk, egg yolks, melted butter and vanilla extract until the yolks are fully incorporated and the liquid is a smooth, pale yellow. You'll smell the rich butter and vanilla straight away.

Whip the egg whites: In a clean, dry bowl (a stand mixer or hand mixer works well), beat the egg whites on medium speed until they form soft peaks. When you lift the whisk, the peaks should flop over gently, not stand stiff. The mixture will look glossy and feel airy.

Combine wet and dry: Pour the buttermilk mixture into the flour bowl. Stir with a rubber spatula until just combined — a few streaks of flour are fine. The batter will look thick and slightly lumpy. Do not overmix, or the pancakes will be tough.

Fold in the egg whites: Gently fold the whipped egg whites into the batter using a figure-of-eight motion. Stop as soon as no white streaks remain. The batter should now be very light, billowy and almost mousse-like in texture. Let it rest for 10 minutes. You'll see tiny bubbles appear on the surface.

Heat the griddle: Place a large non-stick frying pan or griddle over a medium-low heat. Add a small knob of butter and let it melt, tilting the pan to coat the surface. The butter should sizzle gently but not brown immediately. When a drop of water flicked onto the pan dances and evaporates, it's ready.

Cook the pancakes: Pour about 60ml (a scant ¼ cup) of batter onto the hot pan for each pancake, leaving space between them. Cook for 2–3 minutes, or until the edges look set and bubbles start to form and pop on the surface. The underside should be a deep, even golden brown. Flip carefully with a thin spatula and cook for another 1–2 minutes, until the second side is also golden and the pancake feels springy to the touch.

Keep warm: Transfer cooked pancakes to a baking tray lined with parchment paper and keep them in a low oven (about 100°C) while you cook the remaining batter. This keeps them soft and warm without drying them out.